Аннотация:The chapter investigates imbibition into a porous medium under microgravitycondition under the action of capillary forces. The study of capillary effects interrestrial conditions is often difficult due to the influence of gravity, which makesit necessary to conduct experiments in microgravity. The chapter describes thefeatures of experiments and the processing of experimental data in two types ofmicrogravity experiments: during parabolic flights and at space stations in terrestrialorbit. During parabolic flights, a highly permeable artificial porous mediumconsisting of glass balls of the same size was considered (such a medium makes iteasy to visualize experimental results and simulate media with different permeabilityusing balls of different diameters). In experiments in orbit, the flow of fluidswith various physical properties in natural sands was considered. The chapter alsodescribes the mathematical modeling of such processes and presents the results ofnumerical simulations and their comparison with experimental data. The possibilityof determining rheological relationships for capillary forces being functions ofgoverning parameters in porous medium on the basis of data obtained fromexperiments in microgravity is demonstrated.